The need to effectively provide information to a person within a home or other structure pertaining to a person outside a locked entry door to the home or other structure is notoriously well-known. Because of security considerations, the person within may wish to both see the person outside the entry door and converse with the person before determining whether to admit the person through the door. Often, such entry doors are provided with supplementary locking devices (such as the well-known chain lock) which permit limited opening of the door to carry on such visual and aural inspection. Alternatively, a conventional "peep-hole" assembly may be provided which permits the viewer from within a more or less wide angle view of the exterior scene. Additionally, an aural intercommunication system may be provided from the interior of the home or other structure to the exterior of the entry door.
Those skilled in the security arts are well aware of the drawbacks of the "chain lock" devices, most particularly, their vulnerability to simple brute force unauthorized entry attempts. That is, a sufficiently heavy inwardly directed blow to an entry door will result in ripping the locks and related devices from the door and/or the door frame because the effect of the "chain lock" is only as strong as the cumulative effect of the fastening devices, typically wood screws, in the door and door frame. Similarly, peep holes, while useful, unless they provide a very wide angle view, often leave a region (outside the coneshaped field of view) in which an intruder may avoid inspection. With respect to intercommunication devices, all of these systems are useful, but they are typically expensive and are also difficult to install, usually requiring the services of a professional. Thus, those skilled in the security art will appreciate that it would be highly desirable to provide an integrated security intercommunication system for providing both visual and aural information to a person situated on the inside of a closed and locked door with respect to the scene on the outside of the door, which system is simple and inexpensive and may be easily installed by an unskilled person. It is to these ends that our invention is directed.